Blue Wall Didn't Shield Rogue Cop

Police officers did not shield this rogue cop. So how did he continue his behavior for so many years when it was known and documented by so many? Was this political paralysis or was there something more sinister afoot? 

Colleagues Accused Crooked Cop Who Killed Himself of Years of Misconduct: Records - NBC News:

Joseph Gliniewicz — the Illinois cop who committed suicide and tried to make it look like a heroic death in the line of duty — clashed for years with many of his own colleagues, who accused him of extraordinary misbehavior on and off the job, according to his personnel records.